I just found it, Illegal Aliens, by Phil Foglio and Nick Polotta. I may have been spelling Fuerstenberg wrong.
From the Amazon synopsis:
Prof. Rajavur and his 'First Contact Team' had been patiently waiting years for aliens to land on Earth.
Leader Idow and the crew of the starship, All That Glitters, were just looking for an unknown planet where they could land and have a little fun teasing the primitive natives.
So it was pure bad luck that the first humans the alien tricksters encounter is a ruthless New York City street gang, the Bloody Deckers. With more starships landing and the world in chaos, Rajavur and his First Contact Team have to move fast in a desperate plan to rescue the innocent aliens from the evil street gang! Then again, maybe they should join forces with the street gang to protect the Earth from the furious aliens?
Best-Selling author Nick Pollotta and Hugo award winning illustrator Phil Foglio have packed this one-of-a-kind science fiction comedy full of thrilling combat, nuclear agents, planetary blockades, Omega Gas, the galactic police, Russian-doll-style Dyson spheres, a giant flying refrigerator, big juju, a high-stakes game of poker, space battles, warobots, the trail of the millennium, bar fights, naughty lingerie, lost civilizations, the United Nations Space Marines, lost civilizations, group sex, and delicious fried chicken.
From TV Tropes:
Running Gag: PFC Furstenberg is repeatedly field-promoted and -demoted for alternately ridiculously heroic, and unintentionally stupid actions.
- The Space Marines coming up with truly awful nickname candidates for their squad's custom-made rifles.